Volume 20 - 2011
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Signaling Mechanisms in Plants

Feeding the Planet, Saving

the Earth Through



By Sarah Bahari

On the roof of the new Life Sciences Complex, overlooking the University of North Texas campus, grows Medicago truncatula. The greenhouse temperature for the small Mediterranean legume is set at a crisp 70 degrees.

Legumes are unusual in the plant world. Nodules form on the plant roots and are invaded by bacteria, a process that creates fixed nitrogen. This biological phenomenon eliminates or at least lessens the need for synthetic fertilizer in legumes. Researchers at UNT are working to determine how this happens in hopes of one day transferring the process to cereal crops such as corn, wheat, barley, rice and sorghum.

Researchers in UNT's Signaling Mechanisms in Plants cluster

Researchers in UNT's Signaling Mechanisms in Plants cluster include, from left, Brian Ayre, Guido Verbeck, Coordinator Kent Chapman, Jyoti Shah, Rebecca Dickstein, Barney Venables and Amanda Wright. They study how plants use cellular communication in growth, development and stress response.

Photo by: Jonathan Reynolds

A breakthrough of this sort would revolutionize the agricultural industry and ease dependence on synthetic fertilizers, which cost farmers billions of dollars annually and exact a heavy toll on the environment.

"Plants are critical to life on this planet, and they need nitrogen to grow," says Rebecca Dickstein, a biology professor who leads this research project. "But the amount of synthetic nitrogen fertilizer in our atmosphere is not sustainable. Our planet will eventually crash."

Groundbreaking Research

Such groundbreaking research has earned UNT a national reputation in plant science, enabling the university to attract top-level scientists, secure millions of dollars in competitive federal funding — more than $2 million from the National Science Foundation last year alone — and build cutting-edge laboratories. To expand its existing strengths, UNT formed the Signaling Mechanisms in Plants cluster, a collaborative group of researchers who study how plants use cellular communication — a complex network of molecular signals — in their growth, development and defense responses to stress.

Understanding these signaling processes would have far-reaching effects, foremost among them increasing agricultural productivity and feeding the 9 billion people expected to inhabit the planet by 2050. The research also could lead to new technologies in agriculture, nutrition, energy and the environment.

As part of the effort to build and strengthen the cluster, UNT constructed the new Life Sciences Complex, with two floors dedicated primarily to plant science research and four climate-controlled rooftop greenhouses. The university has hired two internationally renowned plant signaling experts and plans to recruit additional faculty researchers in coming months.

Scientists outside UNT have taken notice. Rick Dixon, director of plant biology and senior vice president at the Samuel Roberts Noble Foundation in Ardmore, Okla., says UNT has made an impressive investment unique among universities.

The private research foundation, known and respected internationally for its plant science research, foresees a close relationship with UNT, with one foundation researcher already formally collaborating with the cluster, Dixon says.

"UNT had a very clear vision of what it wanted, and that was excellence," he says. "The university developed a road map for how to achieve that and began executing the plan. The entire initiative came from faculty. It's unusual for a university to build a program in this way, and the efforts are already paying off."

Nitrate Transport

In Dickstein's laboratory, Medicago truncatula, resembling a small clover, has been split at the root and now rests in vials. Researchers are running tests to determine if symbiotic nitrogen fixation occurs in a plant with a defect in a particular gene.

Scientists from UNT, along with the University of Delaware and University of Vermont, were able to clone a gene of the plant, referred to as LATD/NIP. Studies show the gene is crucial to the development of nitrogen-fixing root nodules and suggest it may encode a nitrate transporter. Their findings were published in the spring 2010 cover story of The Plant Journal, a pre-eminent academic journal.

The importance of the research is clear. According to scientists, the use of synthetic nitrogen fertilizer has increased steadily in the past 50 years, growing at a rate of 1 billion tons per year. Artificial nitrogen fertilizers are synthesized using fossil fuels such as natural gas and coal, which are limited. In addition, nitrous oxide is now the third largest greenhouse gas after carbon dioxide and methane.

High levels of synthetic fertilizer can have devastating effects on the environment, creating runoff in rivers and streams that results in dead zones where little can grow or live, Dickstein says. The most notorious of these is in the Gulf of Mexico.

"The use of nitrogen fertilizer is not without consequences," she says. "This is really an energy and environmental issue."

Natural Defenses

Protecting crops against disease and pests also is costly, with farmers worldwide spending billions of dollars a year on pesticides. And each year, they still lose an estimated $100 billion in crops to disease and pests. Arming plants with natural defenses would improve crop productivity and increase the world's food supply, says Jyoti Shah, an associate professor of biology who researches defense mechanisms of plants.

In one project, Shah is studying the green peach aphid, a tiny insect that feeds on more than 50 kinds of plants, including wheat, corn, tomatoes, peaches and peppers. The aphid sucks the sap from plants, interfering with nutrient availability. The insect also transmits more than 100 viral diseases in plants.

UNT researchers discovered that a gene involved in the metabolism of trehalose, a sugar present in trace amounts in plants, can help plants defend against aphids. Using Arabidopsis thaliana, a small weed that serves as a genetic model for studying plant growth, development and stress responses, Shah is examining how this gene and the metabolism of trehalose contribute to defense and if they can be engineered to enhance resistance.

"Improving plant resistance to stress would go a very long way in feeding the world," Shah says. "How can we get plants to contain and control diseases and pests is the question."

Renewable Energy

If scientists could increase the yield of cotton and other crops, plants could be used to make fuel and other renewable energy sources. Scientists already are investigating cost-effective ways to do so. Plants could eventually replace petroleum, a dwindling natural resource, in diesel. Sugars, starches and cellulose can be fermented into ethanol and used for fuel. Plastics could be made with renewable plant sources.

Kent Chapman, Regents Professor of biology and cluster coordinator, researches ways to improve crop yield. Recently, he discovered a mutation in plants that causes oil to accumulate in leaf tissues, essentially regulating the storage of lipids in plants.

This discovery could lead to new agricultural technologies that enhance the lipid content and composition of crops. Producing additional oil in plant leaves and stems could result in more calorie-rich crops to feed people and animals. The additional materials could come from crop parts typically considered waste or from dedicated energy crops, such as switchgrass, used to produce ethanol. A patent on the technology is pending.

Chapman worked with researchers from the University of Texas Southwestern Medical Center, the U.S. Department of Agriculture and the University of Guelph in Canada. The findings were detailed in Proceedings of the National Academy of Sciences in fall 2010.

"Feeding people is, of course, our first priority. But if we can impact crop yield to a certain degree, plants could become a major source of bio-renewable energy," Chapman says. The cluster researchers collaborate on projects with the Renewable Bioproducts cluster, which is using plant, bacteria and other bioagent materials to create ecologically safe products.

Genetic Diversity

Manipulating when crops flower also would improve crop yield. Every spring, farmers in Texas and the South plant cotton to be picked in the fall. However, the crop's genetic diversity has become increasingly limited as it has been bred almost solely for fiber, taking a toll on its resistance to drought, pests and diseases.

Wild cotton, which has a rich gene pool, could be the answer, says Brian Ayre, associate professor of biology. But it flowers at a different time than domesticated cotton. Using a virus-based gene therapy, Ayre manipulates the signals that control flowering time. If the crops could be synchronized, they could cross-pollinate, providing much-needed genetic diversity.

Texas, which produces one-third of the country's cotton supply, has a substantial economic interest in this research.

Victor Shulaev and Ron Mittler

New UNT professors Vladimir Shulaev, left, and Ron Mittler are internationally renowned in the field of plant science. Shulaev's research has applications in crop protection, cancer treatments and nutrition. Mittler works to enhance the tolerance of plants to environmental conditions such as drought, salinity and temperature stress.

Photo by: Jonathan Reynolds

"Cotton is big in Texas and the South," Ayre says. "But the crop is becoming increasingly difficult to grow because its natural defenses are so weak. Manipulating flowering time is one strategy to reverse that trend."

World-class Program

This sort of research has drawn two professors with international reputations to the university: Vladimir Shulaev from Virginia Tech and Ron Mittler from the University of Nevada-Reno. Both joined UNT in 2010 as professors of biology, providing an immediate boost to UNT's efforts, Chapman says.

"These researchers will form a cornerstone for attracting leading scientists focused on understanding the molecular basis of plant signaling processes," he says. "They bring technical expertise that will expand the university's research portfolio."

Shulaev says he was impressed with the potential he saw for UNT to become an international leader in plant science.

"UNT's commitment to science and the interactive, collaborative and interdisciplinary nature of the research is what drew me here. This is how we will create a world-class program."

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Web page last updated or revised: January 11, 2011
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